Removing Efflorescence From Ceramic Tile
- Procedure code:
- Hspg Prepared For Nps - Sero
- Ceramic Tile
- Last Modified:
REMOVING EFFLORESCENCE FROM CERAMIC TILE
THE CLEANING OR REMOVAL OF STAINS FROM TILE MAY INVOLVE THE USE OF
LIQUIDS, DETERGENTS OR SOLVENTS WHICH MAY RUN OFF ON ADJACENT
MATERIAL, DISCOLOR THE TILE OR DRIVE THE STAINS DEEPER INTO POROUS
TILE. USE THE PRODUCTS AND TECHNIQUES DESCRIBED HERE ONLY FOR THE
COMBINATIONS OF DIRT/STAIN AND TILE SPECIFIED.
A. This procedure includes guidance on removing
efflorescence from ceramic tile using a hydrochloric acid
CAUTION: DO NOT USE THIS TREATMENT ON GLAZED TILE.
B. Efflorescence is a condition where white (salt) deposits
form on the surface of the tile. The formation of salts
is usually a sign of excessive amounts of moisture in the
tile. Salt deposits on the tile surface may develop
1. Soluble compounds within the tile or in the soil.
a. In the presence of water, these compounds
gradually migrate to the wall surface, where
they remain when the water evaporates.
b. These types of surface deposits are water
soluble and can usually be removed by washing
the surface with water from a garden hose
supplemented by scrubbing with a stiff bristle
2. Improper or insufficient rinsing of tile after
chemical cleaning or repointing.
3. The penetration of rain into the tile through
deteriorated mortar joints.
4. Exposure to air pollution, which can result in the
formation of thick sulfate (salt) crusts on the
underside of moldings and eaves, areas not
regularly washed by rainfall.
5. Capillary movement of moisture through tile, the
drying out of walls associated with a damp proofing
treatment or the elimination of a ground water
source may increase the amount of salt at or near
the wall surface.
C. These deposits are generally not harmful to the building,
just unattractive. However, they should be washed from
the surface as soon as possible. Some salt deposits are
water-soluble for only a brief period after reaching the
atmosphere. Carbon dioxide in the atmosphere eventually
converts these salts into water-insoluble carbonates,
which are impossible to remove without the use of acids.
D. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precautions
4. Quality Assurance
5. Delivery, Storage and Handling
6. Project/Site Conditions
7. Sequencing and Scheduling
8. General Protection (Surface and Surrounding)
These guidelines should be reviewed prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
NOTE: Chemical products are sometimes sold under a common
name. This usually means that the substance is not as pure as
the same chemical sold under its chemical name. The grade of
purity of common name substances, however, is usually adequate
for stain removal work, and these products should be purchased
when available, as they tend to be less expensive. Common
names are indicated below by an asterisk (*).
A. Hydrochloric Acid (30-35%):
1. A strong corrosive irritating acid.
2. Other chemical or common names include Chlorhydric
acid; Hydrogen chloride; Muriatic acid* (generally
available in 18 degree and 20 degree Baume
solutions); Marine acid*; Spirit of salt*; Spirit
of sea salt*.
3. Potential Hazards: TOXIC, CORROSIVE TO FLESH;
CORROSIVE TO CONCRETE, STEEL, WOOD OR GLASS,
4. Available from chemical supply house, drugstore or
pharmaceutical supply distributor, or hardware
B. Clean, potable water
C. Clean natural fiber rags
A. Garden hose and pneumatic spray nozzle
B. Stiff bristle brushes (non-metallic)
A. Before proceeding with steps to remove efflorescence,
first decide the cause and extent of the problem and make
repairs as required:
1. Determine the age of the structure: Efflorescence
on older buildings is typically caused by the
presence of soluble salts in the construction
combined with moisture.
2. Determine the location of the efflorescence:
Examination may show where the water is entering.
a. Are the salt crystals accumulating on the
joints or on the units?
b. Can any changes in the wall composition or in
the adjacent surroundings be recognized that
might show the source of the problem?
3. Examine the condition of the tile:
a. CAREFULLY EXAMINE the wall for open gaps or
cracks in joints and around openings that
could allow water to enter the building.
1) Are joints properly caulked or sealed?
2) Are flashings and drips in good
3) Are there open or eroded mortar joints in
copings or in sills?
b. Carefully note the condition and profile of
the mortar joints.
c. Repair cracks in tile and/or repoint as
necessary before proceeding with the cleaning
4. Examine wall sections and details of construction:
Carefully examine roof and wall junctures and
flashing details for possible sources of moisture
5. Examine laboratory test reports on the materials:
The problem may stem from the composition or misuse
of the material.
1. Provide adequate wash solutions (i.e. water, soap
and towels) before starting the job.
2. Whenever acid is used, the surface should be
thoroughly rinsed with water as soon as its action
has been adequate. Otherwise it may continue
etching the tile even though the stain is gone.
3.03 ERECTION, INSTALLATION, APPLICATION
NOTE: DO NOT TRY MORE THAN ONE TREATMENT ON A GIVEN AREA
UNLESS THE CHEMICALS USED FROM PRIOR TREATMENT HAVE BEEN
CAUTION: DO NOT USE THIS TREATMENT ON GLAZED TILE.
A. Mix 5% hydrochloric acid in water.
B. Using stiff, natural bristle brushes, scrub the affected
area with the acid solution.
C. Thoroughly rinse the surface with clean, clear water and
allow to dry.
D. Repeat the process as necessary to achieve the desired
level of cleanliness.
END OF SECTION